The present invention relates to a cell culture tank for culture and growth of target cells utilizing adherent cells requiring adherent carriers.
Mass cell culture is a technique essential to the industrial production of the biological medicines, for example, anti-viral drug such as virus, vaccine and interferon, or hormones. Particularly, production of monoclonal antibody for the purpose of producing specific proteins had been impossible in practice until mass culture of hybridoma cells has recently been achieved by hybridization of antibody producing cell and myeloma cell.
The cell culture using adherent cell which requires adherent carrier has conventionally depended on various techniques such as those utilizing roller bottle, multiplate and microcarrier. Among them, the typical technique of mass culture has been the microcarrier method in which the cell culture is performed with the microcarriers floating in culture medium.
However, the microcarrier method of the prior art has been disadvantageous in that the oxygen supply is too limited to maintain a high density cell culture, since the oxygen supply depends on the surface area in such microcarrier method of the prior art.
To overcome such problems, various solutions have been disclosed, for example, in Japanese Patent Disclosure No. 1987-122581, in accordance with which oxygen or oxygen containing gas is supplied from the bottom of the culture tank directly into the culture medium. However, such direct supply of oxygen or oxygen containing gas into the culture medium in which the adherent carriers carrying the cells adhering thereto float has often raised problems that an intense turbulent flow is developed in the culture medium and the cells are damaged by a shearing force of this turbulent flow and that the adherent carriers are driven upward by air bubbles, then adhere to the inner wall of the culture tank at the upper part thereof and the associated means such as sensors, and finally cease to float, interfering with the desired culture.
In view of these problems, the inventors proposed the solution in Japanese Patent Application No. 1987-336366, of which the representative embodiment is shown by FIG. 6 of the accompanying drawing. Referring to FIG. 6, there is provided within a culture tank 51 a cylindrical filter 52 adapted to pass culture medium therethrough but to block adherent carriers 53 with cells adhering thereto. A region 59 surrounded by said filter 52 is filled only with the culture medium and none of the adherent carriers 53 floating therein within this region 59. The culture medium is supplied or drawn off through a conduit 55. Reference numeral 54 designates a conduit used to supply oxygen or air into the region 59. Agitator vanes 56, 57 are driven by an electromotor 58 and serve to agitate the culture medium within the regions 59, 60, respectively.
According to this prior invention of the inventors, the supply of oxygen or air is made only to the region 59 isolated by the filter 52 so that the cells floating outside this region 59 are free from any mechanical damage by a shearing force developed due to turbulent flow and the quantity of culture medium adequately supplied with oxygen in this region 59 permeates through the entire side wall of the filter 52 into the culture medium outside said region 59. Such arrangement enables not only a high density cell culture to be easily achieved but also continuous culture to be maintained for a long period.
However, even such improvement remains disadvantageous in that the agitator vane 57 provided in the region 60 causes a shearing force which may directly damage the cells floating therein.